Patent GB-543701-A (GB)
Title: Improvements in gear cutting machines
IPC: B23F5/12
Filed: 1940-09-05
Abstract: 543,701. Gear-cutting. GLEASON WORKS. Sept. 5, 1940, No. 13905. Convention date, Oct. 18, 1939. [Class 83 (iii)] In a machine for generating bevel gears by means of reciprocating tools moving in converging paths each tool slide is supported on a ram movable by means of a cam in a direction perpendicular to the slide to vary the depth of the cut. The frame carries a sliding base movable on guides 163 perpendicular to the crown wheel plane of the tools which are carried in a cradle 31 journalled in roller bearings 34, 35 and held against axial movement by a flange 41. The cradle is fitted with angularly adjustable tool carriers 45, 451 which may be individually set by pinions 42 engaging circular segments 44 and clamped by a gib 49 and bolts 59. The carrier 45 carries a ram 50 slidable on roller bearings and provided at one end with a guideway 61 on which slides the tool slide 62, each slide being fitted with an adjustable tool T, T<SP>1</SP> which are reciprocated in opposite directions so that they cut alternately on opposite sides of a tooth. The tool slides are reciprocated by a crank mechanism from a shaft 82 through an adjustable crank pin 70, link 71, arm 73 and oscillating shaft 74. This shaft carries an enlarged head 75 fitted with block 76 engaging slots in the tool slides. Radial adjustment of the crank pin 70 is effected from a shaft 85. The shaft 82 carries a cam 90 acting through a lever 91 and roller 98 to impart axial movement to the rams, the rams being urged rearwardly by spring pressure to maintain the rollers 95 against the cam 90. This cam serves not only to withdraw the tools on their non-cutting strokes, but also to move the tools on their cutting strokes so that they follow a non-rectilinear path and impart a crowned form to the gear being cut. The shaft 82 is driven from the main driving motor 100, Fig. 14, through bevel gears 101, change gears 105 and bevel gears 107. The shaft 103 of this train is also connected through gears 114, clutch 117, bevel gears 120, reversing gearing 129, change gears 133, gears 136, shaft 135, bevel gears 138 and worm gearing 142 to the cradle in order to impart generating roll to the cradle in either direction. The clutch 117 enables the tool drive to be isolated for setting up the tools, a hand wheel 146 being used for this purpose. The blank is mounted on a work-spindle 150 carried in a head 151 slidable on a plate 152 to set the work to the required cone distance. The plate 152 is itself angularly adjustable on the base 32 about the central axis x of the machine in accordance with the pitch cone angle of the gear blank. The work spindle is driven in timed relation to the cradle roll by gearing operated by the shaft 135, Fig. 14, and including change gears 173, differential indexing gear 180, shaft 183, bevel gears 184, 189, 192, 195, index change gears 199 and worm gearing 205. After completion of a tooth the work is withdrawn by movement of the base 32, indexed, and then fed back to the tools. These feed and withdrawal movements are effected by a two track feed cam 210 driven from the generating train, Fig. 14, through bevel gears 250 and worm gearing 253. The cam tracks coact with rollers 213 which are brought selectively into position by a pinion 222, Fig. 13, engaging racks on the roll carriers. One of the tracks 211 is used for roughing operations without generating and the other 212 for a finish generating operation. The cams impart movement through a pivoted lever 218 to a housing 236 which embodies a fluid pressure cylinder, the piston rod 239 of which is connected to the base 32. Fluid is admitted to opposite sides of the piston 238 under control of a hand valve for the purpose of effecting an extended withdrawal of the work table for loading and unloading the blanks. The eam 211 for rough cutting gives a continuous depth feed to full depth followed by a withdrawal movement The cam 212 gives a quick feed to full depth followed by a dwell while the tooth is generated and then a withdrawal for indexing. This operation is effected by releasing the housing of the differential mechanism and rotating the same to impart added rotation to the shaft 183 and thus to the work spindle. The housing 178 is normally locked by a dog 260, Fig. 11, carried by a pivoted lever 262 which is normally urged into locking position by a spring plunger carried by a lever 266. The levers 262, 266 carry rollers 270, 272 respectively engaging. different parts of a rotary and reciprocating control member 274 having four control surfaces of which two are cams and two are cylindrical and have radii equal respectively to the minor and major radius portions of the cams. When the dog is in locking position the rollers 270, 272 are respectively on the small and large cylindrical portions holding the parts in the Fig. 11 position. When the control member 274 is shifted axially the rollers are transferred without shock on to the cam parts. This causes both levers to be moved so as to release the locking dog and free the housing which is then rotated through Geneva mechanism. The member 274 is shifted in time with the feed mechanism by a yoke member 297 on a shaft which is rocked by lever mechanism actuated from a cam groove on the feed cam. The control member 274 is mounted on a shaft 275 which is continuously driven from the shaft 122, Fig. 14. When axial movement is imparted to the control member, the roll 317 of the Geneva mechanism is moved into engagement with the slotted wheel 319 and imparts thereto a rotary movement which is transmitted through gears 322 to the differential housing to index the work. Specification 544,700 is referred to. The Specification as open to inspection under Sect. 91 describes also gauging means for positioning roughed-out blanks on the work spindle. In one form this comprises a pivoted member 335 mounted on an adjustable bracket 330, Fig. 16 (Cancelled). A spring normally tends to move the gauge arm to inoperative position. For positioning gears having an uneven number of teeth the gauge is provided with a circumferential rib of increasing size on its periphery the top surface of the rib being concentric with the gauge axis. By using different parts of the circumference blanks having teeth of different pitches may be positioned. Fig. 17 (Cancelled) shows the relation of the gauge to the tools T, T<SP>1</SP> in the case of a fine-pitch gear. For gears having an even number of teeth the gauge has a pair of helical ribs 356, 357 of increasing size round the periphery these ribs being arranged to straddle a tooth as shown in Fig. 19 (Cancelled). In another modification, Fig. 22 (Cancelled), the gauge may be used for setting up blanks with either odd or even numbers of teeth. The subject-matter does not appear in the Specification as accepted.